In case of flattening a thin-plate workpiece such as a silicon wafer, a double-side polishing apparatus or a double-side lapping apparatus has been conventionally used. For example, in the double-side polishing apparatus, a discoid carrier having a planetary gear at an outer peripheral portion thereof is arranged between upper and lower turn tables having polishing pads made of urethane foam or nonwoven fabrics attached thereto. A workpiece is held in a holding hole of this carrier, a sun gear and an internal gear which mesh with the planetary gear are mutually rotated, and a rotational movement of the carrier or an orbital motion of the same around the sun gear is thereby caused. The rotational and orbital motions of this carrier and the rotation of the upper and lower turn tables cause the workplace and the upper and lower turn tables to slide, thereby simultaneously polishing upper and lower surfaces of the workpiece. During the polishing, to efficiently perform the polishing, polishing slurry is supplied from a plurality of holes provided in the upper turn table.
The upper turn table can move up and down, and the carrier can be arranged thereon at an ascending position, or the workpiece is held in the carrier at this position. After the workpiece is held, the upper turn table moves down so that the workpiece and the carrier are sandwiched between the upper and lower turn tables. The workpiece is manually held by an operator or held by using an automatic handling apparatus depending on situations (see, e.g., Patent Literature 1).
The upper turn table is moved up and down by an upper turn table support mechanism which supports the upper turn table from above. The upper turn table support mechanism includes a cylinder having a shaft which can move an and down, and the shaft of the cylinder is coupled with the upper turn table through a connecting section. For example, a universal joint or a spherical bearing is used for this connecting section. That is because, when a thickness of the workpiece to be polished or the carrier varies, a degree of freedom is imparted to an inclination of the upper turn table during the polishing so that a load can be assuredly transmitted to the workpiece.